A CMP (chemical mechanical polishing) device includes a polishing device for polishing a surface of a semiconductor substrate on which a semiconductor chip is formed and a cleaning device for cleaning the semiconductor substrate polished by the polishing device while supplying a cleaning chemical. This cleaning device creates a cleaning chemical (diluted chemical) by a chemical with mixing dilution water such as DIW (De-Ionized Water) and cleans the semiconductor substrate by using the cleaning chemical (see, for example, Japanese Patent Laid-Open No. 2009-54959).
Cleaning devices using a cleaning chemical conventionally use a CLC (closed loop controller) that measures a flow rate of a liquid and controls the flow rate based on the measured value. The CLC can control flow rates of the chemical and DIW and supply the chemical which is diluted at a predetermined ratio to the cleaning device.
As a flowmeter provided inside the CLC, a differential pressure type flowmeter (orifice flowmeter) is generally used. With an orifice placed in a path through which a fluid passes, the differential pressure type flowmeter measures a volume flow rate (flow speed) of the fluid based on the differential pressure. A measurement range of the differential pressure type flowmeter, that is, a flow rate range that can be controlled by the CLC structurally falls within a range predetermined according to a diameter of the orifice, for example, from 30 ml/min to 300 ml/min. For example, in the case of the CLC provided with an ultrasonic type flowmeter, its controllable flow rate range is defined to be a predetermined range.
In the conventional cleaning chemical supplying device, when a dilution ratio of the cleaning chemical is changed in association with a change in a process recipe or the like or when a flow rate of the cleaning chemical supplied is changed, the flow rates of the required chemical and the DIW may deviate from the flow rate range that can be controlled by the currently selected CLC. In that case, the change in the process recipe is handled by replacing the CLC by a CLC having a controllable flow rate range.